Method of manufacturing a steel component having a head part and a hollow shank part

ABSTRACT

To manufacture a steel component having a head part and a hollow shank part, a steel slug is positioned in a die cavity having a narrow portion which defines the shape of the shank part of the required component. One end of the slug extends into the narrow portion of the die cavity and engages a first punch defining the shape of the bore in the hollow shank part, whereas the other end of the slug extends into a wide portion of the die cavity and engages a second punch. The first and second punches are then caused to undergo relative movement towards each other so that the first punch enters the one end of the slug. As the first punch enters the slug, it produces the required bore for the shank part of the component and the region of the slug surrounding the first punch moves relative thereto substantially without constraint. Also, in entering the slug, the first punch causes metal to flow towards the other end of the slug and into the wide portion of the die cavity, which is so dimensioned that the metal is not constrained to conform to the shape of the wide portion of the die cavity.

United States Patent [191 Lawson et a1.

[11] 3,835,686 Sept. 17, 1974 METHOD OF MANUFACTURING A STEEL COMPONENT HAVING A HEAD PART AND A HOLLOW SHANK PART [75] Inventors: Ralph Leonard Joseph Lawson;

Zygmunt Jablonski, both of Birmingham, England [73] Assignee: The Lucas Electrical Company, Limited, Birmingham, England 22 Filed: Mar. 7, 1973 21 Appl. No.: 338,946

[30] Foreign Application Priority Data Mar. 28. 1972 Great Britain 14410/72 [52] US. Cl. 72/354, 72/358 [51] Int. Cl B21k 21/08 [58] Field of Search .72/354, 356, 358, 359; 10/86 F, 26 E [56] References Cited UNITED STATES PATENTS 3,283,556 11/1966 Putetti et a1. 72/354 3,540,255 11/1970 Hanna 10/86 F 3,589,164 6/1971 Constant 72/354 3,651,683 3/1972 Liebergeld 72/354 Primary ExaminefRichard J. Herbst Attorney, Agent, or FirmHill, Gross, Simpson, Van Santen, Steadman, Chiara & Simpson [5 7] ABSTRACT To manufacture a steel component having a head part and a hollow shank part, a steel slug is positioned in a die cavity having a narrow portion which defines the shape of the shank part of the required component. One end of the slug extends into the narrow portion of the die cavity and engages a first punch defining the shape of the bore in the hollow shank part, whereas the other end of the slug extends into a wide portion of the die cavity and engages a second punch.

The first and second punches are then caused to undergo relative movement towards each other so that the first punch enters the one end of the slug. As the first punch enters the slug, it produces the required bore for the shank part of the component and the region of the slug surrounding the first punch moves relative thereto substantially without constraint. Also, inentering the slug, the first punch causes metal to flow towards the other end of the slug and into the wide portion of the die cavity, which is so dimensioned that the metal is not constrained to conform to the shape of the wide portion of the die cavity.

8 Claims, 5 Drawing Figures PATENIED S E PI 7:914

' SHEEI 1 OF 3 Hal FIGZ. 4

PATENTEU SEP 1 71974 3. 835.686

SHEET 3 BF 3 METHOD OF MANUFACTURING A STEEL COMPONENT HAVING A HEAD PART AND A HOLLOW SHANK PART This invention relates to a method of manufacturing a steel component having a head part and a hollow shank part.

A method, according to a first aspect of the invention, includes the steps of:

a. starting with a steel slug and positioning the slug in a die cavity so that one end of the slug is received in a narrow portion of the die cavity and engages a first punch defining the shape of the bore in the hollow shank part of the component, and so that the other end of the slug extends into a wide portion of the die cavity and engages a second punch, said narrow portion of the die cavity defining the shape of the shank part of the finished component, and

b. causing the first and second punches to undergo relative movement towards each other so that the first punch enters said one end of the slug to produce the required bore for the shank part of the component and causes metal to flow towards the other end of the slug, said wide portion of the die cavity being so shaped that metal tends to flow into said wide portion, but being so dimensioned that the metal is not constrained to conform to the shape of the wide portion, and the arrangement also being such that the region of said one end of the slug surrounding the first punch moves relative to the first punch, as the punch enters the slug, substantially without constraint.

A method, according to a second aspect of the invention, includes the steps of:

a. starting with a steel slug and positioning the slug in a die cavity so that one end of the slug is received in a narrow portion of the die cavity and engages a first punch defining the shape of the bore in the hollow shank part of the component, and so that the other end of the slug extends into a wide portion of the die cavity and engages a second punch, said narrow portion of the die cavity defining the shape of the shank part of the finished component,

b. causing said first and second punches to undergo relative movement towards each other so that the first punch enters said one end of the slug to produce the required bore for the shank part of the component and causes metal to flow towards the other end of the slug, said wide portion of the die cavity being so shaped that metal tends to flow into said wide portion, but being so dimensioned that the metal is not constrained to conform to the shape of the wide portion, and the arrangement also being such that the region of said one end of the slug surrounding the first punch moves relative to the first punch substantially without constraint until said region is held against further movement by an abutment surrounding the first punch, and then causing the first punch and the abutment to move relative to the die cavity to compress the shaped slug between the second punch and the first punch, and between the second punch and the abutment.

Conveniently said abutment is in the form of a hollow punch surrounding said first punch, the hollow punch being capable of limited movement relative to the first punch, with a fixed stop serving to limit movement of the hollow punch so that, when engaging the fixed stop, the hollow punch prevents movement of said region of the slug relative to the first punch.

In a third aspect, the invention resides in a method of manufacturing a roller clutch sleeve of the kind having a head portion and a shank portion, the bore in the sleeve being stepped to define a wide portion within the head portion and a narrow portion within the shank portion, and the wall of the wide portion of the bore defining an internal cam surface in the head portion, the method including the steps of starting with a component manufactured in accordance with the second aspectof the invention so that the hollow shank part of the component defines the shape of the shank portion of the sleeve, and further including the steps of:

d. producing a bore in the head part of the component which communicates with the bore in the shank part, and

e. with the head part of the component in position in a die cavity defining the shape of the head portion of the sleeve, using a further punch to perform an impact extrusion operation on the component so that metal flows from the head part to conform to the shape of the die cavity and so that, after extrusion, the bore in the head part conforms to the required shape of the wide portion of the bore in the sleeve.

Preferably, step (d) is performed by a piercing tool.

Preferably, the steel slug is produced by cropping a substantially cylindrical steel bar so that the slug has a length to diameter ratio of not less than 0.75 and a diameter substantially equal to the external diameter of the shank part of the component.

Most preferably, the length to diameter ratio of the cropped slug is greater than one.

Preferably, where the slug is produced by a cropping operation, the slug is then heat treated to remove any work. hardening produced during cropping.

In the accompanying drawings,

FIG. 1 is a sectional view of a roller clutch sleeve, and

FIGS. 2 to 5 are sectional views illustrating four stages respectively during a method according to a first example of the invention of producing the sleeve shown in FIG. 1.

Referring to FIG. 1, it is desired to manufacture a roller clutch sleeve 9, the sleeve having a cylindrical head portion 9a and a cylindrical shank portion 9b joined to the head portion by a tapering portion 90. The bore 10 in the sleeve 9 is stepped to define a wide portion 10a in the head portion 9a and a narrow portion 10b in the shank portion 9b, and the wall of the wide portion 10a is arranged to define an internal cam surface (not shown) in the head portion 9a.

As shown in FIGS. 2 to 5, in one example of the invention, the sleeve 9 was manufactured from a cylindrical steel bar '11, conveniently a centreless, turned steel bar 11, or alternatively a bright drawn steel bar or an as-rolled bar. The bar 11 was first fed into a cropping tool 12 and was cropped to produce a slug 13, the feeding of the bar 11 into the tool 12 being controlled by means of a fixed stop (not shown) so that the cropping operation produced a slug 13 of predetermined weight, the weight of the slug to be formed being determined by the volume of the slug necessary to produce a tinished sleeve 9 of the desired dimensions. In this particular example, the tool 12 was arranged to produce a slug 13 of weight between 480 and 500 grams and length 2. [75 inch. The diameter of the slug was arranged to be substantially equal to the diameter of the shank portion 9b of the sleeve and to have a value of 1.535 inch. The slug 13 was then heat treated to remove any work hardening of the steel which may have resulted during the cropping operation. Conveniently, the heat treatment was a normalising operation, with the slug 13 being heated at 925C for 1 hour, or alternatively the heat treatment was a spheroidising operation, with the slug being heated at 680C for 4 hours. Following heat treatment, the slug 13 was lubricated by a standard phosphating and soaping treatment and was positioned in the die cavity 14 of an extrusion die set 15. It is, however, to be appreciated that means other than cropping could have been employed to obtain the slug 13, such as, for example, sawing or turning, in which case heat treatment of the slug may not have been necessary.

As shown in FIG. 3, the die cavity 14 was defined in a die part 21 and included a narrow, cylindrical portion 14a and a wide, cylindrical portion 14b. The portion 14a had a diameter substantially equal to the external diameter of the shank portion 9b of the sleeve 9 and the portion 14b. a diameter substantially equal to the external diameter of the head portion 9a. The slug 13 was positioned in the die cavity 14 so that one end 13a of the slug engaged a punch assembly 16 extending into the portion 140 and so that the other end 13b of the slug extended into the portion 14b of the cavity. The punch assembly 16 included a central, fixed punch 18, defining the shape of the narrow portion b of the bore in the sleeve 9, and an outer, hollow punch 19 slidable relative to the punch 18 and die cavity 14. In addition, the die part 21 was resiliently mounted above a base 22 of the die set, and hence was slidable relative to the punch assembly 16 towards and away from the base 22. A further punch 17 was secured to a movable platen (not shown) of the die set by way of a support assembly 31 which was positioned above the die part 21. Thus, during movement of the movable platen, the assembly 31 engaged the die part 21 so that, during further movement of the platen, the punch 17 was effectively secured to the die part 21 so that the punch 17 and the die part 21 moved together. Removable spacers (not shown) were provided within the assembly 31 so that, prior to movement of the movable platen, the position of the punch 17 in relation to the die cavity 14 could be adjusted.

When the slug 13 was in position in the die cavity 14, a forming operation was performed on the slug by applying a load of 190 tons to the punch 17 to urge the punch 17 and therefore the die part 21 and the slug 13 towards the punch assembly 16. The fixed punch 18 was thereby forced to enter the end 13a of the slug, while the movable punch 19 was urged by the slug to slide with the die part 21 towards the base 22. As the punch 18 entered the slug 13 metal was displaced from the slug and was forced to flow into the portion 14b of the die cavity to produce an expanded head portion of the slug (FIG. 4), metal flow into the portion 14b being aided by an inclined surface 14c defining part of the wall of the portion 14b. Further the punch 17, the surface and the wall of the portion 14b were arranged so that together they defined an annular space 20 of volume greater than the total volume of metal displaced towards the end 13b of the slug during the forming operation so that, at all times, the displaced metal flowed freely into the portion 14b and was not constrained to conform to the shape of the portion 14b. In the particular example, the portion 14b had a diameter of 2.32 inch and it was found that the preferred volume for the space 20 was obtained when the maximum axial distance between the punch 17 and the surface 140 was 0.650 inch. In fact, it was found that, only by ensuring that metal flowed substantially freely during the forming operation, was it possible to maintain the stresses on the punch 18 within tolerable limits. Also, it is to be understood that since the punch 19 was arranged to be slidable relative to the punch 18, the region of the end 13a of the slug surrounding the punch 18 was able to move during the forming operation substantially without constraint.

As can be seen from FIGS. 3 and 4, to limit the distance the punch 18 entered the slug 13 during the forming operation, a fixed stop 23 was positioned in the path of movement of the punch 19. Thus, on engaging the stop 23, the punch 19 defined an abutment preventing further movement of the punch 19 relative to the punch 18, and hence further movement of the punch 18 into the slug 13. However, the arrangement was such that when the punch 19 engaged the fixed stop 23 to prevent further movement of the punch 19, the die parts 21 and punch 17 were capable of further movement relative to the punch assembly 16. Thus, during the forming operation, movement of the punch 17 first caused the punch 18 to enter the slug 13 until the punch 19 engaged the fixed stop 23, whereafter during further movement of the punch 17 the formed slug was compressed between the punch 17 and the punches 18, 19 to complete formation of the head portion of the slug and produce the component 24 shown in FIG. 4. Of course, by varying the arrangement of the spacers within the assembly 31 which controlled the position of the punch 17 relative to the die part 21, it was possible to control the amount the formed slug 13 was compressed to produce the component 24. Also, it will be appreciated that, in production, once the correct position of the punch 17 relative to the die part 21 has been established, there should be no need to further modify the arrangement of the spacers in the assembly 31.

By following the method of forming the slug 13 described above, it was found to be possible to avoid cracking in the expanded head portion of the slug.

In the particular example described, the component 24 had an overall length of l.775 inch and included a head part 24a of maximum diameter 2.32 inch. The component further included a hollow shank part 24b defining the shank portion 9b of the required roller clutch sleeve, the diameter of the bore in the part 24b being 0.782 inch. Following forming, the component 24 was removed from the die 15 and the head part 24a was pierced to produce a bore in the head part communicating with and of the same diameter as the bore in the shank part 24b. The pierced component was then treated at 680C for 4 hours, whereafter the component was lubricated by a standard phosphating and soaping application.

The lubricated component 24 was then positioned in an extrusion die 25 and an impact extrusion operation was performed on the component. In this case, extrusion was effected by applying a load of 242 tons through an extrusion punch 26 to the free end of the head portion 24a of the component. During extrusion, a mandrel 27 was positioned in the bore in the component 24 and the free end of the hollow shank portion 24b of the component was held against movement by a stationary punch 28, whereby application of pressure to the component 24 through the punch 26 caused flow of metal in the opposite direction to the direction of movement of the punch. The arrangement of the die 25 was such that flow of metal during this backward extrusion process further shaped the preform 24 to define the head part 9a of the finished sleeve 9 which, in this particular example, had a tapering portion 90 defining an included angle of 140. Furthermore, the punch 26 was shaped to produce the required internal cam surface in the head part 9 and also to produce a plurality of integral, spaced ribs 29 extending inwardly from the wall of the wide portion 10a of the bore 10. It is to be appreciated that in a roller clutch assembly, each of the ribs 29 defines an abutment against which a spring is flexed so as to urge a roller into engagement with the cam surface on the wall of the wide portion 10a of the bore 10. However, it is to be understood that the ribs need not be formed integral with the sleeve 9, but could be formed by mounting separate pins in the stepped part of the wall of the bore 10 in the sleeve.

In a modification of the above example, the method described above was repeated, but in this modification, the final sleeve 9 was required to have reduced overall dimensions, as compared with the sleeve produced in the preceding example. Thus, the steel bar 11 was cropped to produce a slug of weight between 215 and 220 grams, of length 2.92 inch, and of diameter 0.7973 inch. Following heat treatment and lubrication, the slug was formed in the die 15 by applying a pressure of 150 tons to the punch 17, with the punch being secured relative to the die part 21 so that the maximum axial distance between the surface 14c and the punch 17 was between 0.5 and 0.7 inch. The component 24 thus produced had an overall length of 1.6 inch, a head portion 24a of maximum diameter of 0.85 inch, which was arranged to be substantially equal to the diameter of the head part 9a of the finished sleeve 9, and had a hollow shank portion 24b defining the shank part 9b of the finished sleeve, with the bore in the portion 24b having a diameter of 0.64 inch. As in the previous example, the head portion 24a was then pierced to produce a bore extending through the component and, following heat treatment and lubrication, an impact extrusion operation was performed on the head portion 24a by applying a load of 145 tons to the punch 26. In this particular example, the tapering portion 9c of the sleeve 9 was arranged to define an included angle of 170.

The component produced in the example described above, together with the modification thereof is particularly designed for use as a roller clutch sleeve for a starter motor. In some cases, however, the component 24 produced at an intermediate stage of the method may define a desirable end product, in which case, of course, further processing of the component to produce a roller clutch sleeve would not be performed.

In producing the component 24 described above, it was necessary to impart relative movement between the die cavity and the punches l8, 19 when the punches were held against movement relative to one another, so

as to increase the diameter of the expanded head portion of the component. It is, however, to be appreciated that for other applications, such movement may not be required, in which case formation of the component would not involve this additional operation.

Also it is to be understood that, whereas in the example quoted, the punch 17 and die part 21 were held stationary relative to one another during the forming operation on the slug 13, the component 24 could have been produced by allowing the punch 17 to enter the die cavity and move relative thereto during the forming process. In this case, it would have been necessary to arrange that the required volume of material in the head portion 24a was obtained when the permitted relative movement of the punches was complete.

Furthermore, it is to be appreciated that before the sleeve shown at 9 can be used to form part of a roller clutch assembly helical grooves must be produced in the wall of the narrow portion 10b of the bore for engagement with complementary splines on the rotor shaft of the starter motor.

We claim:

1. A method of manufacturing a steel component having a head part and a hollow shank part, including the steps of:

a. positioning a steel slug in a die cavity so that one end of the slug is received in a'narrow portion of the die cavity and engages a first punch defining the shape of the bore in the hollow shank part of the component, and so that the other end of the slug extends into a wide portion of the die cavity and engages a second punch, said narrow portion of the die cavity defining the shape of the shank part of the finished component and said wide and narrow portions of the die cavity being defined within a single-piece die part, and moving at least one of the first and second punches to provide relative movement of the punches towards each other so that the first punch enters said one end of the slug to produce the required bore for the shank part of the component and causes metal to flow towards the other end of the slug, said wide portion of the die cavity being so shaped that metal tends to flow into said wide portion, but being so dimensioned that the metal is not constrained to conform to the shape of the wide portion and the arrangement also being such that the region of said one end of the slug surrounding the first punch moves relative to the first punch, as the punch enters the slug, substantially without constraint.

2. A method of manufacturing a steel component having a head part and a hollow shank part, including the steps of:

a. positioning a steel slug in a die cavity so that one end of the slug is received in a narrow portion of the die cavity and engages a first punch defining the shape of the bore in the hollow shank part of the component and so that the other end of the slug extends into a wide portion of the die cavity annd engages a second punch, said narrow portion of the die cavity defining the shape of the shank part of the finished component and said wide and narrow portions of the die cavity being defined within a single-piece die part,

b. moving at least one of said first and second punches to provide relative movement of the punches towards each other so that the first punch enters saidone end of the slug to produce the required bore for the shank part of the component and causes metal to flow towards the other end of the slug, said wide portion of the die cavity being so shaped that metal tends to flow into said wide portion, but being so dimensioned that the metal is not constrained to conform to the shape of the wide portion, and the arrangement also being such that the region of said one end of the slug surrounding the first punch moves relative to the first punch substantially without constraint until such region is held against further movement by an abutment surrounding the first punch, and then 0. moving the first punch and the abutment relative to the die cavity to compress the shaped slug between the second punch and the first punch, and between the second punch and the abutment.

3. A method as claimed in claim 2 wherein said abutment is in the form of a hollow punch surrounding said first punch, the hollow punch being capable of limited movement relative to the first punch, with a fixed stop serving to limit movement of the hollow punch so that, when engaging the fixed stop, the hollow punch prevents movement of said region of the slug relative to the first punch.

4. A method of manufacturing a roller clutch sleeve of the kind having a head portion and a shank portion, the bore in the sleeve being stepped to define a wide portion within the head portion and a narrow portion within the shank portion, and the wall of the wide portion of the bore defining an internal cam surface in the head portion, the method including the steps of starting with a component manufactured by a method as claimed in claim 2 so that the hollow shank part of the component defines the shape of the shank portion of the sleeve, and further including the steps of:

d. producing a bore in the head part of the component which communicates with the bore in the shank part, and

e. with the head part of the component in position in a die cavity defining the shape of the head portion of the sleeve, using a further punch to perform an impact extrusion operation on the component so that metal flows from the head part to conform to the shape of the die cavity and so that, after extrusion, the bore in the head part conforms to the required shape of the wide portion of the bore in the sleeve.

5. A method as claimed in claim 4 wherein step (d) is performed by a piercing tool.

6. A method as claimed in claim 2 wherein the steel slug is produced by cropping a substantially cylindrical steel bar so that the slug had a length to diameter ratio of not less than 0.75 and a diameter substantially equal to the external diameter of the shank part of the component.

7. A method as claimed in claim 6 wherein the length to diameter ratio of the cropped slug is greater than one.

8. A method as claimed in claim 6 wherein, after cropping, the slug is heat treated to remove any work hardening producing by the cropping operation. 

1. A method of manufacturing a steel component having a head part and a hollow shank part, including the steps of: a. positioning a steel slug in a die cavity so that one end of the slug is received in a narrow portion of the die cavity and engages a first punch defining the shape of the bore in the hollow shank part of the component, and so that the other end of the slug extends into a wide portion of the die cavity and engages a second punch, said narrow portion of the die cavity defining the shape of the shank part of the finished component and said wide and narrow portions of the die cavity being defined within a single-piece die part, and b. moving at least one of the first and second punches to provide relative movement of the punches towards each other so that the first punch enters said one end of the slug to produce the required bore for the shank part of the component and causes metal to flow towards the other end of the slug, said wide portion of the die cavity being so shaped that metal tends to flow into said wide portion, but being so dimensioned that the metal is not constrained to conform to the shape of the wide portion and the arrangement also being such that the region of said one end of the slug surrounding the first punch moves relative to the first punch, as the punch enters the slug, substantially without constraint.
 2. A method of manufacturing a steel component having a head part and a hollow shank part, including the steps of: a. positioning a steel slug in a die cavity so that one end of the slug is received in a narrow portion of the die cavity and engages a first punch defining the shape of the bore in the hollow shank part of the component and so that the other end of the slug extends into a wide portion of the die cavity annd engages a second punch, said narrow portion of the die cavity defining the shape of the shank part of the finished component and said wide and narrow portions of the die cavity being defined within a single-piece die part, b. moving at least one of said first and second punches to provide relative movement of the punches towards each other so that the first punch enters said one end of the slug to produce the required bore for the shank part of the component and causes metal to flow towards the other end of the slug, said wide portion of the die cavity being so shaped that metal tends to flow into said wide portion, but being so dimensioned that the metal is not constrained to conform to the shape of the wide portion, and the arrangement also being such that the region of said one end of the slug surrounding the first punch moves relative to the first punch substantially without constraint until such region is held against further movement by an abutment surrounding the first punch, and then c. moving the first punch and the abutment relative to the die cavity to compress the shaped slug between the second punch and the first punch, and between the second punch and the abutment.
 3. A method as claimed in claim 2 wherein said abutment is in the form of a hollow punch surrounding said first punch, the hollow punch being capable of limited movement relative to the first punch, with a fixed stop serving to limit movement of the hollow punch so that, when engaging the fixed stop, the hollow punch prevents movement of said region of the slug relative to the first punch.
 4. A method of manufacturing a roller clutch sleeve of the kind having a head portion and a shank portion, the bore in the sleeve being stepped to define a wide portion within the head portion and a narrow portion within the shank portion, and the wall of the wide portion of the bore defining an internal cam surface in the head portion, the method including the steps of starting with a component manufacTured by a method as claimed in claim 2 so that the hollow shank part of the component defines the shape of the shank portion of the sleeve, and further including the steps of: d. producing a bore in the head part of the component which communicates with the bore in the shank part, and e. with the head part of the component in position in a die cavity defining the shape of the head portion of the sleeve, using a further punch to perform an impact extrusion operation on the component so that metal flows from the head part to conform to the shape of the die cavity and so that, after extrusion, the bore in the head part conforms to the required shape of the wide portion of the bore in the sleeve.
 5. A method as claimed in claim 4 wherein step (d) is performed by a piercing tool.
 6. A method as claimed in claim 2 wherein the steel slug is produced by cropping a substantially cylindrical steel bar so that the slug had a length to diameter ratio of not less than 0.75 and a diameter substantially equal to the external diameter of the shank part of the component.
 7. A method as claimed in claim 6 wherein the length to diameter ratio of the cropped slug is greater than one.
 8. A method as claimed in claim 6 wherein, after cropping, the slug is heat treated to remove any work hardening producing by the cropping operation. 